08Request

1.request对象和response对象的原理

1. request和response对象是由服务器创建的。我们来使用它们
2. request对象是来获取请求消息，response对象是来设置响应消息

2. request对象继承体系结构

ServletRequest        --    接口
            |    继承
        HttpServletRequest    -- 接口
            |    实现
        org.apache.catalina.connector.RequestFacade 类(tomcat)

3. request功能

3.1 获取请求消息数据

1. 获取请求行数据
　　 GET /day14/demo1?name=zhangsan HTTP/1.1
　　方法：
　　1. 获取请求方式：GET
　　     String getMethod()
　　2. (*)获取虚拟目录：/day14
　　　　 String getContextPath()
　　3. 获取Servlet路径: /demo1
　　　　String getServletPath()
　　4. 获取get方式请求参数：name=zhangsan
　　　　String getQueryString()
　　5. (*)获取请求URI：/day14/demo1
　　　　String getRequestURI():        /day14/demo1
　　　　StringBuffer getRequestURL()  :http://localhost/day14/demo1

　　　　　　URL:统一资源定位符： http://localhost/day14/demo1    中华人民共和国
　　　　　　URI：统一资源标识符 : /day14/demo1                    共和国（范围更大）

　　6. 获取协议及版本：HTTP/1.1
　　　　 String getProtocol()

　　7. 获取客户机的IP地址：
　　　　String getRemoteAddr()

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/RequestDemo1")

public class RequestDemo1 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //1. 获取请求方式 ：GET

        String method = request.getMethod();

        System.out.println(method);

        //2.(*)获取虚拟目录：/day14

        String contextPath = request.getContextPath();

        System.out.println(contextPath);

        //3. 获取Servlet路径: /demo1

        String servletPath = request.getServletPath();

        System.out.println(servletPath);

        //4. 获取get方式请求参数：name=zhangsan

        String queryString = request.getQueryString();

        System.out.println(queryString);

        //5.(*)获取请求URI：/day14/demo1

        String requestURI = request.getRequestURI();

        StringBuffer requestURL = request.getRequestURL();

        System.out.println(requestURI);

        System.out.println(requestURL);

        //6. 获取协议及版本：HTTP/1.1

        String protocol = request.getProtocol();

        System.out.println(protocol);

        //7. 获取客户机的IP地址：

        String remoteAddr = request.getRemoteAddr();

        System.out.println(remoteAddr);

    }

}

2. 获取请求头数据
　　方法：
　　　　 (*)String getHeader(String name):通过请求头的名称获取请求头的值
　　　　 Enumeration<String> getHeaderNames():获取所有的请求头名称

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.util.Enumeration;

@WebServlet("/RequestDemo2")

public class RequestDemo2 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //演示获取请求头数据

        //1.获取所有请求头名称

        Enumeration<String> headerNames = request.getHeaderNames();

        //2.遍历

        while(headerNames.hasMoreElements()){

            String name = headerNames.nextElement();

            //根据名称获取请求头的值

            String value = request.getHeader(name);

            System.out.println(name+"---"+value);

        }

    }

}

3. 获取请求体数据:
　　请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数
　　步骤：
　　1. 获取流对象
　　BufferedReader getReader()：获取字符输入流，只能操作字符数据
　　ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据
　　在文件上传知识点后讲解
　　 2. 再从流对象中拿数据

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.util.Enumeration;

@WebServlet("/RequestDemo3")

public class RequestDemo3 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //演示获取请求头数据:user-agent

        String agent = request.getHeader("user-agent");

        //判断agent的浏览器版本

        if(agent.contains("Chrome")){

            //谷歌

            System.out.println("谷歌来了...");

        }else if(agent.contains("Firefox")){

            //火狐

            System.out.println("火狐来了...");

        }

    }

}

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

    <form action="/demo3" method="POST">

        <input name="username">

        <input type="submit" value="提交">

    </form>

<hr>

<a href="/day13Servlet/RequestDemo4">demo4...</a>

</body>

</html>

package cn.itcast.web.request;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/RequestDemo4")

public class RequestDemo4 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //演示获取请求头数据:referer

        String referer = request.getHeader("referer");

        System.out.println(referer);

        //防盗链

        if(referer != null ){

            if(referer.contains("/day14")){

                //正常访问

               // System.out.println("播放电影....");

                response.setContentType("text/html;charset=utf-8");

                response.getWriter().write("播放电影....");

            }else{

                //盗链

                //System.out.println("想看电影吗？来优酷吧...");

                response.setContentType("text/html;charset=utf-8");

                response.getWriter().write("想看电影吗？来优酷吧...");

            }

        }

    }

}

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>注册页面</title>

</head>

<body>

    <form action="/day13Servlet/RequestDemo5" method="post">

        <input type="text" placeholder="请输入用户名" name="username"><br>

        <input type="text" placeholder="请输入密码" name="password"><br>

        <input type="submit" value="注册">

    </form>

</body>

</html>

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.BufferedReader;

import java.io.IOException;

@WebServlet("/RequestDemo5")

public class RequestDemo5 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取请求消息体--请求参数

        //1.获取字符流

        BufferedReader br = request.getReader();

        //2.读取数据

        String line = null;

        while((line = br.readLine()) != null){

            System.out.println(line);

        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

}

3.2 其他功能

1. 获取请求参数通用方式：不论get还是post请求方式都可以使用下列方法来获取请求参数
　　1. String getParameter(String name):根据参数名称获取参数值 username=zs&password=123
　　2. String[] getParameterValues(String name):根据参数名称获取参数值的数组 hobby=xx&hobby=game
　　3. Enumeration<String> getParameterNames():获取所有请求的参数名称
　　4. Map<String,String[]> getParameterMap():获取所有参数的map集合

　　中文乱码问题：
　　　　 get方式：tomcat 8 已经将get方式乱码问题解决了
　　　　 post方式：会乱码
　　　　解决：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>注册页面</title>

</head>

<body>

    <form action="/day13Servlet/RequestDemo6" method="post">

        <input type="text" placeholder="请输入用户名" name="username"><br>

        <input type="text" placeholder="请输入密码" name="password"><br>

        <input type="submit" value="注册">

    </form>

</body>

</html>

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.BufferedReader;

import java.io.IOException;

import java.util.Enumeration;

import java.util.Map;

import java.util.Set;

@WebServlet("/RequestDemo6")

public class RequestDemo6 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //post 获取请求参数

        //根据参数名称获取参数值

        String username = request.getParameter("username");

       /* System.out.println("post");

        System.out.println(username);*/

       //根据参数名称获取参数值的数组

        String[] hobbies = request.getParameterValues("hobby"); //主要是复选框用

        /*for (String hobby : hobbies) {

            System.out.println(hobby);

        }*/

        //获取所有请求的参数名称

        Enumeration<String> parameterNames = request.getParameterNames();

        /*while(parameterNames.hasMoreElements()){

            String name = parameterNames.nextElement();

            System.out.println(name);

            String value = request.getParameter(name);

            System.out.println(value);

            System.out.println("----------------");

        }*/

        // 获取所有参数的map集合

        Map<String, String[]> parameterMap = request.getParameterMap();

        //遍历

        Set<String> keyset = parameterMap.keySet();

        for (String name : keyset) {

            //获取键获取值

            String[] values = parameterMap.get(name);

            System.out.println(name);

            for (String value : values) {

                System.out.println(value);

            }

            System.out.println("-----------------");

        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //get 获取请求参数

/*

        //根据参数名称获取参数值

        String username = request.getParameter("username");

        System.out.println("get");

        System.out.println(username);*/

        this.doPost(request,response);

    }

}

2. 请求转发：一种在服务器内部的资源跳转方式
　　1. 步骤：
　　　　1. 通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)
　　　　2. 使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response)

　　2. 特点：
　　　　1. 浏览器地址栏路径不发生变化
　　　　2. 只能转发到当前服务器内部资源中。
　　　　3. 转发是一次请求

package cn.itcast.web.request;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/RequestDemo8")

public class RequestDemo8 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("demo8888被访问了。。。");

        //转发到demo9资源

/*

        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");

        requestDispatcher.forward(request,response);

        */

        //存储数据到request域中

        request.setAttribute("msg","hello");

        request.getRequestDispatcher("/RequestDemo9").forward(request,response);

        //request.getRequestDispatcher("http://www.itcast.cn").forward(request,response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);

    }

}

package cn.itcast.web.request;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/RequestDemo9")

public class RequestDemo9 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取数据

        Object msg = request.getAttribute("msg");

        System.out.println(msg);

        System.out.println("demo9999被访问了。。。");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);

    }

}

3. 共享数据：
　　　　域对象：一个有作用范围的对象，可以在范围内共享数据
　　　　request域：代表一次请求的范围，一般用于请求转发的多个资源中共享数据
　　　　方法：
　　　　1. void setAttribute(String name,Object obj):存储数据
　　　　2. Object getAttitude(String name):通过键获取值
　　　　3. void removeAttribute(String name):通过键移除键值对

4. 获取ServletContext：
　　　　ServletContext getServletContext()

package cn.itcast.web.request;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/RequestDemo10")

public class RequestDemo10 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        ServletContext servletContext = request.getServletContext();

        System.out.println(servletContext);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);

    }

}

4.登录案例

用户登录案例需求：

1.编写login.html登录页面
username & password 两个输入框
2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表
3.使用JdbcTemplate技术封装JDBC
4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

4.1开发步骤

1. 创建项目，导入html页面，配置文件，jar包

2. 创建数据库环境

CREATE DATABASE day14;

USE day14;

CREATE TABLE USER(

    id INT PRIMARY KEY AUTO_INCREMENT,

    username VARCHAR(32) UNIQUE NOT NULL,

    PASSWORD VARCHAR(32) NOT NULL

);

3. 创建包cn.itcast.domain,创建类User

package cn.itcast.domain;

/**

 * 用户的实体类

 */

public class User {

    private int id;

    private String username;

    private String password;

    private String gender;

    public void setHehe(String gender) {

        this.gender = gender;

    }

    public String getHehe() {

        return gender;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

    @Override

    public String toString() {

        return "User{" +

                "id=" + id +

                ", username='" + username + '\'' +

                ", password='" + password + '\'' +

                ", gender='" + gender + '\'' +

                '}';

    }

}

4.创建包cn.itcast.util,编写工具类JDBCUtils

package cn.itcast.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;

import javax.xml.crypto.Data;

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.Properties;

/**

 * JDBC工具类 使用Durid连接池

 */

public class JDBCUtils {

    private static DataSource ds;

    static {

        try {

            //1.加载配置文件

            Properties pro = new Properties();

            //使用ClassLoader加载配置文件，获取字节输入流

            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");

            pro.load(is);

            //2.初始化连接池对象

            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {

            e.printStackTrace();

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    /**

     * 获取连接池对象

     */

    public static DataSource getDataSource() {

        return ds;

    }

    /**

     * 获取连接Connection对象

     */

    public static Connection getConnection() throws SQLException {

        return ds.getConnection();

    }

}

5. 创建包cn.itcast.dao,创建类UserDao,提供login方法

package cn.itcast.dao;

import cn.itcast.domain.User;

import cn.itcast.util.JDBCUtils;

import org.springframework.dao.DataAccessException;

import org.springframework.jdbc.core.BeanPropertyRowMapper;

import org.springframework.jdbc.core.JdbcTemplate;

/**

 * 操作数据库中User表的类

 */

public class UserDao {

    //声明JDBCTemplate对象共用

    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    /**

     * 登录方法

     * @param loginUser 只有用户名和密码

     * @return user包含用户全部数据,没有查询到，返回null

     */

    public User login(User loginUser){

        try {

            //1.编写sql

            String sql = "select * from user where username = ? and password = ?";

            //2.调用query方法

            User user = template.queryForObject(sql,

                    new BeanPropertyRowMapper<User>(User.class),

                    loginUser.getUsername(), loginUser.getPassword());

            return user;

        } catch (DataAccessException e) {

            e.printStackTrace();//记录日志

            return null;

        }

    }

}

6. 编写cn.itcast.web.servlet.LoginServlet类

package cn.itcast.web.servlet;

import cn.itcast.dao.UserDao;

import cn.itcast.domain.User;

import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;

import java.util.Map;

@WebServlet("/LoginServlet")

public class LoginServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //1.设置编码

        req.setCharacterEncoding("utf-8");

       /* //2.获取请求参数

        String username = req.getParameter("username");

        String password = req.getParameter("password");

        //3.封装user对象

        User loginUser = new User();

        loginUser.setUsername(username);

        loginUser.setPassword(password);*/

        //2.获取所有请求参数

        Map<String, String[]> map = req.getParameterMap();

        //3.创建User对象

        User loginUser = new User();

        //3.2使用BeanUtils封装

        try {

            BeanUtils.populate(loginUser,map);

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        } catch (InvocationTargetException e) {

            e.printStackTrace();

        }

        //4.调用UserDao的login方法

        UserDao dao = new UserDao();

        User user = dao.login(loginUser);

        //5.判断user

        if(user == null){

            //登录失败

            req.getRequestDispatcher("/FailServlet").forward(req,resp);

        }else{

            //登录成功

            //存储数据

            req.setAttribute("user",user);

            //转发

            req.getRequestDispatcher("/SuccessServlet").forward(req,resp);

        }

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        this.doGet(req,resp);

    }

}

package cn.itcast.web.servlet;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/FailServlet")

public class FailServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //给页面写一句话

        //设置编码

        response.setContentType("text/html;charset=utf-8");

        //输出

        response.getWriter().write("登录失败，用户名或密码错误");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);

    }

}

package cn.itcast.web.servlet;

import cn.itcast.domain.User;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/SuccessServlet")

public class SuccessServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取request域中共享的user对象

        User user = (User) request.getAttribute("user");

        if(user != null){

            //给页面写一句话

            //设置编码

            response.setContentType("text/html;charset=utf-8");

            //输出

            response.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");

        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);

    }

}

注意：跳转的路径应该和tomcat中配置一样，否则会找不到资源，404错误。

8. login.html中form表单的action路径的写法
　　虚拟目录+Servlet的资源路径

9. BeanUtils工具类，简化数据封装
　　用于封装JavaBean的
　　1. JavaBean：标准的Java类
　　　　1. 要求：
                    1. 类必须被public修饰
                    2. 必须提供空参的构造器
                    3. 成员变量必须使用private修饰
                    4. 提供公共setter和getter方法
                2. 功能：封装数据

　　2. 概念：
                成员变量：
                属性：setter和getter方法截取后的产物
                    例如：getUsername() --> Username--> username

　　3. 方法：
                1. setProperty()
                2. getProperty()
                3. populate(Object obj , Map map):将map集合的键值对信息，封装到对应的JavaBean对象中

巴特西